Abstract
NO single animal has provided such a rich field for discovery in genetics as the little fruit-fly Drosophila (usually known as D. ampelophila, but now called D. melanogaster), and in this large and handsomely illustrated volume Prof. Morgan and his collaborators bring together the results of some of their recent work upon it. Of the four parts into which the book is divided, the most interesting is the first, dealing with the gynandromorphic specimens that have appeared in Prof. Morgan's and Dr. Bridges's experiments, and including a most valuable summary and discussion of gynandromorphism in other animals. In Drosophila it appears that about one individual in every 2200 is gynandromorphic, but these gynandromorphs are most varied in their combination of male and female characters. A considerable proportion of those described are bilateral, with male secondary sex-characters on one side and female on the other; a smaller number are “fore and aft”; while the majority are irregular mosaics, most often with a preponderance of female characters. It is a remarkable fact, however, that in Drosophila, contrary to what is usual in animals of other groups, the two gonads are always of the same sex—doubtless, as the authors point out, in consequence of the very early separation of the primitive germ-cells in the Diptera. As a result of this, it may happen that a fly is externally almost entirely of one sex while containing germ-cells of the other sex, so that Nature here confirms the conclusion reached by Meisenheimer and by Kopeč from transplantation experiments, that the sex of the gonad in insects has no influence on the secondary sexual characters. Flies externally chiefly male, but having ovaries instead of testes, court normal females, but attract males.
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DONCASTER, L. Genetic Studies of Drosophila1. Nature 105, 405–406 (1920). https://doi.org/10.1038/105405a0
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DOI: https://doi.org/10.1038/105405a0